Cannabis sativa Linn. is an annual herb of Cannabis Linn., Cannabinaceae, and the flower, leaf and stem products of its mature female plants are called Marijuana. Currently, cannabinoids (CBs) isolated from marijuana plants are of more than 80 kinds, which mainly includes tetrahydrocannabinol (THC), cannabidiol (CBD), cannabinol (CBN), cannabichromene (CBC) and the like, where the contents of THC and CBD are the highest.
THC is one of the important active ingredients in Cannabis sativa. It has a good neuroprotective effect and can be used to treat cancer-induced vomiting. However, due to its hallucinogenic effect, only a cannabis variety which has a THC content in flowers and leaves during the growth period of less than 0.3% (i.e. industrial cannabis) is allowed to be planted.
CBD, which was isolated from Cannabis sativa in the nineteen forties, is another important active ingredient in Cannabis sativa, and is also an important non-addictive active ingredient of Cannabis sativa. Through in vivo experiments, it is found that, CBD not only can antagonize the mental activities induced by THC-activated cannabinoid type I receptor (CB1R), but also has anticonvulsive, sedative-hypnotic, anxiolytic, antipsychotic, anti-inflammatory and neuroprotective effects, and is a natural active ingredient that is highly promising in the fields of medicine and food.
It is a premise for the development and application of CBD to remove THC and other ingredients with hallucinogenic and addictive effects as much as possible, so as to obtain a high-purity product. Currently, in publicly available information, there are some reports on methods for extracting CBD from industrial cannabis. For example, CN105505565A and CN105535111A respectively disclose a method for preparing a CBD-enriched cannabis oil or cannabis extract by using a supercritical or subcritical extraction technology; CN107011125A discloses a method for enriching cannabidiol, where the specific process includes two steps, i.e., conducting carbon dioxide supercritical extraction to obtain a preliminary extract of cannabis flowers and leaves, and then performing column chromatography, wherein the medium used for the column chromatography is AB-8, D-101, DA-201, HPD-100, HPD-100A, LSA-10, MCIGEL, DIAION or SEPABEADS, and the like styrene macroporous adsorption resins or silica gels; CN106831353A discloses another method for extracting cannabidiol, where the specific process includes alcohol extraction and water precipitation, column chromatography, crystallization, and the like steps, where the medium used for the column chromatography is AB-8, D-101, XDA-8, LSA-7, D-941, DM-130, ADS-17, SP-825 or HPD-600, and the like macroporous adsorption resins, a MCI resin or an octadecyl bonded silica gel, etc., and the crystallization solvent is ethanol.
The marijuana plant has complex phenolic ingredients and many ingredients with similar polarities. Therefore, even in the case that the ethanol crystallization process of CN106831353A is used to prepare CBD, hallucinogenic or addictive ingredients such as THC can still be detected in the product, which affects the safety of the CBD product.